V1, 9500i (and 9500xi) and Bel STi are all top of the line. But each has unique features.

V1 - direction arrows.
9500 - GPS database of red-light locations (and other things) to warn you when you approach them.
STi - cannot be detected by radar-detector-detectors. (Although 9500 is pretty good with this too.) Very important in VA, DC and other places where radar detectors are not allowed.

Each has a money back guarantee so get all three, play with them for 30 days, then send the two lowest on your list back.